Make sure that the billing address for your Xbox Live account matches the billing address you use with your credit card company. Also, make sure that your card's expiration date hasn't passed. Here's how:

On the "Change how you pay for these subscriptions" page, select the payment option to change from the drop-down list.
Note To add a new payment option, select Add a new way to pay, select Next, and then follow the steps to set up your credit card, debit card, or PayPal account as a new payment option.

Once you've selected the option to be changed, select Next, and then follow the instructions to change your payment option.